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As Penrose freely admits, his other main theory is far more speculative. It holds that consciousness and insight, which he says are beyond the capabilities of computers, are governed by as yet undiscovered laws of physics. The idea that computers are necessarily unconscious and without insight is largely based on his own experience in solving abstract puzzles. And it is true that these mental processes are not explained by existing laws of physics. The answers will come, says Penrose, with the merger of Einstein's theory of relativity, which concerns itself with gravity, and quantum theory, which governs the sub-microscopic world. These two theories are mathematically incompatible, and physicists are hard at work trying to create a quantum version of gravity.
One consequence could be to establish the boundaries of quantum mechanics, which says particles can suddenly jump from one place to another without traversing the space in between. Penrose's intuition, although he has no proof, is that these effects may apply not just to atoms but also to objects as big as brain cells. An act of creative thinking, he argues, could be the outward manifestation of neurons making quantum jumps from one energy state to another. Since computers do not operate by quantum rules, he says, they will never have insights.
Moreover, he believes, quantum gravity could be behind consciousness itself. The argument is tricky, but one reason for this belief is that consciousness carries with it a peculiarity that baffles physics: humans perceive time as moving forward rather than backward. But virtually all the laws of physics are time symmetric -- they work equally well in forward or in reverse -- and the mind presumably operates by physical laws.
Penrose's answer is that when quantum gravity is finally constructed, it will prove to be time asymmetric -- that is, it will not work in reverse. Why? Because the Big Bang that started the universe must, at its earliest moments, have been governed by quantum gravity. And the Big Bang was surely a time- asymmetric phenomenon that could not happen in reverse. If quantum gravity winds up being the theory governing the mind, that will also explain why time moves forward, not backward.
In short, Penrose believes human creativity and consciousness are nothing less than the perceptible workings of the most basic laws of the universe. It is a bolder position than other physicists are prepared to take, but Penrose likes to be different. Says he: "Worrying about things that no one else worries about is where insights come from."